Electronic equipment, including equipment based on semiconductor technology, is susceptible to damage or upsets from High Altitude Electromagnetic Pulse (HEMP or EMP), Intentional Electromagnetic Interference (IEMI) and RF interference. For example, stored data in modern electronic data systems, control systems and recording systems can be upset, scrambled or lost by EMP, IEMI or RF energy. At higher energy levels of EMP, IEMI or RF power the semiconductor devices within electronics units can be destroyed.
Damage based on exposure to electromagnetic fields is not limited to semiconductor-based systems. For example, EMP and IEMI events can cause interference or damage to electrical equipment, causing that equipment to malfunction or rendering it nonoperational. Electrical equipment can also be destroyed by strong electromagnetic pulse (EMP), intentional electromagnetic interference (IEMI) or high power RF radiation. The detailed characteristics of EMP radiation are described in Military Standard 188-125, entitled “High Altitude Electromagnetic Pulse Protection for Ground Based C4I Facilities Performing Critical, Time-Urgent Missions”. The detailed characteristics of IEMI are described in IEC Standard 61000-2-13, “High-power electromagnetic (HPEM) environments-Radiated and conducted.”
In general, EMP/IEMI/RF events typically take one of two forms. First, high field events correspond to short-duration, high electromagnetic field events (e.g., up to and exceeding 100 kilovolts per meter), and typically are of the form of short pulses of narrow-band or distributed signals (e.g., in the frequency range of typically 14 kHz to 10 GHz). These types of events typically generate high voltage differences in equipment, leading to high induced currents and burnout of electrical components. Second, low field events (e.g., events in the range of 0.01 to 10 volts per meter) are indications of changing electromagnetic environments below the high field damaging environments, but still of interest in certain applications.
Existing electromagnetic protection schemes are typically used to protect against a narrow range of threats. The protection schemes built into electronic systems are generally developed to address a certain possible issue, are not useful to address other electromagnetic interference issues. Although attempts have been made to “harden” or protect, certain military systems against these threats, many commercial electronic systems remain unprotected. However, these existing “hardening” solutions are cost-prohibitive to apply to a wide range of electronics, exposing critical assets to possible damage. Additionally, existing solutions provide some amount of shielding, but are not designed to accommodate all of the cooling and access considerations required of many modern electronic systems. Additionally, earlier shielding attempts could at times limit the functionality of electronics included in such systems, since at times power or other signals would be entirely disrupted to avoid damage to internal electronics. Because the vast majority of electronics remain unprotected from EMP/IEMI/RF events, a widespread outage or failure due to electromagnetic interference could have disastrous effects.
For these and other reasons, improvements are desirable.